A blood pump device such as an artificial heart assist device has been known as a device for assisting circulation of blood of a patient who has suffered from malfunction or the like of an organ such as a heart. There are various kinds of blood pump devices. For example, there is a blood pump device in which a centrifugal pump is used for sucking and discharging a fluid by a centrifugal force caused by a rotation of an impeller. As an example of the centrifugal pump-typed blood pump device, a centrifugal blood pump device is disclosed in Patent Document 1 which includes a housing having a blood inlet port and a blood outlet port and an impeller that rotates in the housing and feeds blood using a centrifugal force in rotating.